A model to predict phase equilibrium of CH (sub 4) and CO (sub 2) clathrate hydrate in aqueous electrolyte solutions
A model to predict phase equilibrium of CH (sub 4) and CO (sub 2) clathrate hydrate in aqueous electrolyte solutions
American Mineralogist (August 2006) 91 (8-9): 1346-1354
- aliphatic hydrocarbons
- alkanes
- aqueous solutions
- carbon dioxide
- clathrates
- electrolytes
- equations
- experimental studies
- gas hydrates
- geochemistry
- hydrocarbons
- laboratory studies
- marine sediments
- methane
- numerical analysis
- ocean floors
- organic compounds
- phase equilibria
- saline composition
- sediments
- stability
- thermodynamic properties
A thermodynamic model to predict phase equilibrium of methane and carbon dioxide hydrate in aqueous electrolyte solutions is presented. Using the Pitzer model to account for the variation of water activity due to electrolytes and dissolved gas in aqueous solutions, we extended the model based on ab initio molecular potential developed recently by us for the CH (sub 4) -H (sub 2) O and CO (sub 2) -H (sub 2) O binary systems to the CH (sub 4) (or CO (sub 2) )-H (sub 2) O-salts system. Comparison of the model with extensive experimental data indicates that this model can accurately predict the phase equilibrium of CH (sub 4) hydrate and CO (sub 2) hydrate in various electrolyte solutions (such as aqueous NaCl, KCl, CaCl (sub 2) , NaCl + KCl, NaCl + CaCl (sub 2) solutions, and seawater) from zero to high ionic strength (about 6 m) and from low to high pressures.